JP5609184B2 - Radar apparatus and frequency control program - Google Patents

Description

  The present case relates to a radar apparatus and a frequency control program for detecting a target.

  In general, when a radar device is used for driving support of an automobile, the distance measurement range is from several meters to hundreds of tens of meters, the measurement speed is from 0 km / h to ± 200 km / h, and weather conditions and Regardless of the time zone, it is required to stably detect various objects including pedestrians, motorcycles, and large vehicles. At the same time, it is necessary to identify whether the preceding vehicle existing in the forward direction of the own vehicle is on the own lane necessary for vehicle control or the vehicle existing in the adjacent lane, regardless of whether it is a straight road or a curved road. is there. Therefore, it is required to detect the relative lateral position (angle), and it is necessary to scan the emitted radio wave within a predetermined angle range.

  As in the case of using electronic devices for communication, multipath is one of the radio interferences that frequently occur in such radar devices. There are various paths for the transmission wave from the radar apparatus being used to reach the communication partner or detection target, and the radio wave also reaches the communication partner or detection target through these paths. For this reason, a phase difference occurs between radio waves arriving through the respective paths, and the multipath is strengthened or canceled by the phase difference.

  If the received power reflected from the target by multipath is low when the radar is used, correct detection cannot be performed, causing undetected or erroneous detection. There are various modulation methods such as FM-CW, two-frequency CW, pulse, spread spectrum (SS) method, etc. in the method of capturing a millimeter wave from a radar device and supplementing the target. Is a problem.

  As a vehicle-mounted radar device that prevents false detections due to radio interference including interference, the center frequency of the transmitted wave is periodically shifted, and a majority decision is made based on the position information of obstacles detected at each frequency. There is one in which an erroneous obstacle detection result due to an obstacle is excluded (for example, see Patent Document 1).

JP 2004-109046 A JP-A-6-66934 JP 2004-117246 A

  However, when the target that is the detection target moves, the phase difference between the multipath radio waves changes due to the movement, and depending on the distance of the target from the radar, the reception level may decrease and detection may not be possible. There was a problem.

  This case has been made in view of the above points, and provides a radar device and a frequency control program that prevent undetected and erroneous detection by switching to a frequency at which received power reaches a peak and transmitting radio waves. The purpose is to do.

  In order to solve the above problems, a radar apparatus is provided. The radar apparatus includes a transmission unit that outputs a transmission wave, a reception unit that receives a reflected wave reflected by the target of the transmission wave, and a reception within a predetermined range based on the reflected wave received by the reception unit. A control unit that changes the frequency of the transmission wave output by the transmission unit when it is detected that the target of a level exists.

  In order to solve the above problem, a frequency control program for a radar apparatus is provided that includes a transmission unit that outputs a transmission wave and a reception unit that receives a reflected wave reflected by the target of the transmission wave. When the frequency control program detects that the target having a reception level within a predetermined range exists based on the reflected wave received by the receiving unit, the frequency control program outputs the transmission wave output by the transmitting unit. It functions as a control means for changing the frequency.

  According to the disclosed radar apparatus and frequency control program, it is possible to prevent target non-detection and false detection.

It is a figure which shows the radar apparatus which concerns on 1st Embodiment. It is a figure explaining the image of multipass. It is a figure which shows the relationship between the distance between AB of FIG. 2, and the reception level of the reflected wave in A point. It is a figure which shows the hardware structural example of the millimeter wave radar apparatus which concerns on 2nd Embodiment. It is a functional block diagram of CPU of FIG. It is a figure which shows the calculation result which changed the frequency condition. It is a figure explaining the reception power after a frequency change. It is a figure explaining the change timing of a frequency. It is a figure explaining the procedure which calculates | requires the distance between paths. It is a figure explaining another example of timing of variable frequency. It is a flowchart which shows the operation | movement procedure at the time of the frequency switching of a radar apparatus. It is a figure which shows an example which uses a radar apparatus for the vehicle approach detection in an intersection. It is a figure which shows an example which uses a radar apparatus for measurement of a throwing distance.

Hereinafter, a first embodiment will be described in detail with reference to the drawings.
FIG. 1 is a diagram illustrating a radar apparatus according to the first embodiment. As shown in FIG. 1, the radar apparatus 10 includes a transmission unit 1, a reception unit 2, and a control unit 3. The transmitter 1 and the receiver 2 are connected to the antenna 4 of the radar apparatus 10. FIG. 1 also shows the target 5 detected by the radar apparatus 10.

  The transmitter 1 outputs a radio wave set to a predetermined frequency from the antenna 4 toward the target 5. This radio wave is reflected by the target 5, and the receiving unit 2 receives the reflected radio wave (reflected wave) via the antenna 4.

Based on the reflected wave received by the receiving unit 2, the control unit 3 changes the frequency of the transmission wave of the transmission unit 1 when detecting that the target 5 having a reception level within a predetermined range exists.
Next, an example of multipath will be described.

  FIG. 2 is a diagram illustrating a multipath image. In FIG. 2, it is assumed that the radar apparatus 10 is at point A and the target 5 to be detected is at point B, and that both are located at a distance R1 in a linear distance.

  The radar apparatus 10 at point A transmits radio waves from the antenna 4 in a plurality of directions in order to detect the presence of the target 5 at point B. At that time, a direct wave RAB and a plurality of indirect waves are assumed as a route of the radio wave reaching the target 5. Among a plurality of indirect waves, as a representative one that affects the detection of the target 5 of the radar apparatus 10, the light is reflected at the center of the ground G (point C at the center of points A and B) and reaches the target 5. An indirect wave RACB is conceivable.

  That is, the direct wave RAB and the indirect wave RACB reach the target 5, and the electric power of the radio wave received by the target 5 is a power obtained by combining the two radio waves. And the electric power of the radio wave received by the target 5 changes according to the phase difference between the direct wave RAB and the indirect wave RACB.

For example, in the target 5, if the direct wave RAB and the indirect wave RACB arrive in the same phase, the power received by the target 5 increases, but decreases if it reaches the opposite phase.
If the power of the radio wave received by the target 5 is reduced, the power of the reflected wave reflected from the target 5 is also reduced. If it does so, the electric power of the reflected wave which the radar apparatus 10 receives will also become small, and the undetected and false detection of the target 5 will arise.

  The phase difference φ between the direct wave RAB and the indirect wave RACB arriving at the target 5 is the wavelength λ of the radio wave set by the radar device 10, the distance R1 between the target 5 and the antenna 4 to be detected, and the antenna 4 and the target, respectively. It is determined by the heights h1 and h2 from the ground G of 5. A phase difference φ generated between the direct wave RAB having the distance R1 and the indirect wave RACB having the path length R2 is expressed by the following equation (1).

φ = (R2-R1) · 2π / λ (1)
FIG. 3 is a diagram showing the relationship between the distance between A and B in FIG. 2 and the reception level of the reflected wave at point A. As an example, FIG. 3 shows the result of calculating the power level of the radio wave at point A when the radio wave frequency is 76 GHz and the incoming power of the direct wave RAB and the indirect wave RACB to the target 5 is the same. ing. Here, it is assumed that the ground height h1 of the antenna 4 of the radar apparatus 10 is 1 m, and the ground height h2 of the target 5 is 1 m.

As the influence of the multipath on the reflected wave received by the radar apparatus 10, the following phenomenon can be pointed out from FIG.
As the distance to the target (distance between A and B) increases, not only the reception level (dB) at point A decreases, but also null points at which reflected waves cannot be received periodically occur. Further, since the width of the null point increases as the distance from the radar apparatus 10 to the target 5 increases, the non-detection range of the target 5 also increases. FIG. 3 shows an example of threshold values for the radar apparatus 10 to detect the presence of the target 5. In FIG. 3, the threshold value is, for example, −50 dB. The radar apparatus 10 determines that the target 5 does not exist when the reception level of the reflected wave is smaller than −50 dB.

  That is, when the distance is less than 100 m, the non-detection range is 1 m or less even if it is continuous. However, as the distance increases, the non-detection range continues longer, and the 2-m range of 134 to 136 m or 154 to 158 m The non-detection range continues in the 4m range. This is because, in the case of a radar device for detecting a traveling vehicle as a target, a vehicle that has once entered a non-detection range is continuously in a non-detection state over a range of several meters, thereby constituting a radar system. It was a big problem above.

  By the way, as described above, the generation of the null point is related to the wavelength λ. Therefore, the radar apparatus 10 can reduce the influence of multipath by switching the set frequency of radio waves and changing the wavelength λ thereof.

  Therefore, when the control unit 3 of the radar apparatus 10 detects the presence of the target 5 having a reception level within a predetermined range based on the reflected wave received by the reception unit 2, the frequency of the transmission wave of the transmission unit 1 is detected. To change. That is, for example, when the target 5 is about to approach the non-detection range, the control unit 3 of the radar apparatus 10 changes the frequency of the transmission wave and moves the null point.

  For example, in the example of FIG. 3, the control unit 3 changes the frequency of the transmission wave of the transmission unit 1 when the reception level of the reflected wave received by the reception unit 2 is −50 dB or more and −45 dB or less. . As a result, the null point moves, and the radar apparatus 10 can prevent the target 5 from being undetected or erroneously detected.

  Further, the radar apparatus 10 changes the frequency of the transmission wave when the reception level of the reflected wave is within a predetermined range. That is, the radar apparatus 10 changes the frequency of the transmission wave to a frequency at which the target 5 can be easily detected when the target 5 exists, and does not change the frequency of the transmission wave when the target 5 does not exist. Thereby, the radar apparatus 10 can suppress power consumption.

Next, a second embodiment will be described in detail with reference to the drawings.
FIG. 4 is a diagram illustrating a hardware configuration example of the millimeter wave radar device according to the second embodiment.

  The millimeter wave radar apparatus 100 includes a radar transmission / reception unit 11, a reception power measurement unit 12, a reception frequency measurement unit 13, a CPU 14, a memory 15, a signal generation unit 16, and a scanner control unit 17. The millimeter wave radar apparatus 100 includes a scanner 18 whose rotation is controlled in the vertical direction by the scanner control unit 17 and a radar antenna 19 as a planar antenna that rotates integrally with the scanner 18.

The radar transmission / reception unit 11 transmits a millimeter wave by the radar antenna 19 and performs signal processing of a reflected wave from the received target.
The reception power measuring unit 12 outputs reception level information necessary for target extraction to the CPU 14 by measuring the power of the reception signal.

The reception frequency measurement unit 13 measures the frequency of the received millimeter wave signal and outputs frequency information necessary for distance measurement to the CPU 14.
The CPU 14 controls the rotation of the scanner 18 via the scanner control unit 17. The CPU 14 also controls the millimeter wave transmission frequency in the signal generator 16.

  The memory 15 stores a program for the CPU 14 to control the frequency of the signal generator 16. The memory 15 also stores various data necessary for the processing of the CPU 14 such as distance measurement to the target.

  The radar antenna 19 transmits a millimeter wave set to a predetermined transmission frequency while controlling the rotation of the scanner 18. Here, a radar system using a millimeter-wave band radio wave that can detect a situation in the range of about several hundreds of meters by receiving a radio wave reflected from a target (not shown) by a radar antenna 19. Is configured.

  Since the millimeter wave radar device 100 uses millimeter waves with excellent straightness, the millimeter wave radar device 100 can be used in fog, rain, and snow. For example, the millimeter wave radar device 100 can be used as an in-vehicle radar for the purpose of collision reduction. is there. Currently, the frequency bands that can be used as millimeter waves are the 60 GHz band and the 76 GHz band, and various technical conditions are defined as low-power millimeter-wave radars.

  In the case of the millimeter wave radar device 100, a threshold is set for the power level in the received power measuring unit 12, and if the power level is higher than the threshold, the presence of the target is detected, and if the power level is lower, there is no target. to decide.

FIG. 5 is a functional block diagram of the CPU of FIG.
The CPU 14 includes a separation distance measurement unit 141, a multipath path length measurement unit 142, and a frequency calculation unit 143.

The separation distance measurement unit 141 receives the reception frequency signal from the reception frequency measurement unit 13 and calculates the distance between the antenna 4 and the target 5.
The multipath route length measurement unit 142 calculates the multipath route length based on the distance calculated by the separation distance measurement unit 141.

  The frequency calculation unit 143 includes the frequency of the reflected wave measured by the reception frequency measurement unit 13, the distance calculated by the separation distance measurement unit 141, and the multipath path length calculated by the multipath path length measurement unit 142. Based on the above, the frequency of the transmission wave to be changed is calculated. The frequency calculation unit 143 calculates the frequency of the transmission wave to be changed when the reception level of the reflected wave measured by the reception power measurement unit 12 is within a predetermined threshold range set by the initial setting, for example. For example, as described with reference to FIG. 3, the frequency calculation unit 143 calculates the frequency of the transmission wave to be changed based on the parameter when the reception level of the reflected wave is between −50 dB and −45 dB.

  The memory 15 temporarily stores calculation results from the above-described separation distance measurement unit 141, multipath path length measurement unit 142, and frequency calculation unit 143. The frequency calculation unit 143 is connected to the signal generation unit 16 and the memory 15, and calculates a newly set frequency value based on the calculation result stored therein.

FIG. 6 is a diagram illustrating a calculation result with varying frequency conditions.
Here, the calculation result obtained by changing the frequency condition with respect to FIG. 3 is shown, and the generation distance of the null point that changes by changing the radar frequency (= λ) is shown.

  In FIG. 6, when the distance to the target (A-B distance) is 154 to 158 m, the reception level of 76 GHz is a null point, and if the target exists in this range, it will not be detected. On the other hand, when the reception level of 82 GHz is seen even in the same distance range, a peak value is almost shown. If such a radio wave is transmitted, a reception level necessary for target detection is sufficiently secured. By utilizing such a phenomenon and converting the frequency of the transmission wave according to the received power, it becomes possible to eliminate the non-detection area.

Next, consider the relationship between frequency, radar height, and distance that show peaks due to multipath.
The typical received power affected by the multipath is a combination of the direct wave power and the reflected wave power of the ground in FIG. 2 and is expressed by the following equation (2).

Pm = Pd · Pr | cosφ | (2)
From equation (2), when | cosφ | = 1, Pm has a peak, so the wavelength λ (frequency) when φ = nπ (n is an integer) may be obtained. Further, from the equation (1), this equation becomes 2πδ / λ = nπ (n is an integer), so that the following equation (3) is obtained.

2δ / λ = n (n is an integer, λ is the wavelength of the transmitted wave) (3)
As in the case of FIG. 2, assuming that the radar frequency is 76 GHz under the conditions of the radar ground height h1 = 1 m and the detection target ground height h2 = 1 m, the left side of the expression (3) is 6. 5 If the decimal point of 6.5 is rounded up to an integer of 7, the radar frequency at this time is 82 GHz. On the other hand, when the decimal point of 6.5 is rounded down to an integer of 6, the radar frequency at this time is 70.3 GHz.

FIG. 7 is a diagram for explaining the received power after the frequency change.
As shown in the figure, even at 82 GHz when n is rounded up to 7 and at 70.3 GHz when rounded down to 6 is received, the reception level is sufficient to compensate for the null point generated at a distance of 154 to 158 m to the target. Is obtained.

  If the left side of equation (3) is calculated in this way and the frequency at which the received power reaches a peak (near the radar frequency at the null point) is calculated by rounding up or down after the decimal point, switching is performed as shown in FIG. , The received power in the area that becomes the null point at 76 GHz can be peaked by switching the radar frequency to 70.3 GHz or 82 GHz, and sufficient received power for detection can be ensured.

FIG. 8 is a diagram for explaining the frequency change timing.
Here, the moving target B is moved away from the radar apparatus 10 installed at the point A on the straight line (A), and the moving target B and the radar apparatus 10 installed at the point A are a plurality of moving targets C and D. The case of the same figure (B) detected by this will be described.

  Even if the target of B1 is detected at a radar frequency of 82 GHz, for example, as shown in FIG. 8A, it may not be detected when the target moves to B2. In such a case, for example, the null point can be avoided by switching the radar frequency to the original 76 GHz again.

  Here, the detectable distance of the radar apparatus 10 is 100 m. The radar apparatus 10 may switch the radar frequency to the original 76 GHz when the target no longer exists within the detectable distance 100 m.

  In FIG. 8B, when two targets C and D are being detected simultaneously, when either one of the targets C and D cannot be detected, the radar frequency is switched to, for example, 82 GHz.

In this case as well, the radar apparatus 10 may switch the radar frequency to the original 76 GHz when the target no longer exists within the detectable distance 100 m.
FIG. 9 is a diagram illustrating a procedure for obtaining a distance between routes.

  Here, an image different from the multipath image in FIG. 2 is assumed. That is, consider a case where the radar apparatus 10 is installed at a point A at a height of h3 from the ground, and the target B exists at h4 from the ground.

  Assume that the radar device 10 at the point A detects a reflected wave from the target B when it is swung to an angle θ by the scanner. Then, the distances AB and AC in the right triangle ABC can be obtained from the angle θ and the straight line distance R3 between AB. Accordingly, the path distance R4 (= R41 + R42) of the indirect wave reflected at the intermediate point D and reaching the target can be obtained, and the path difference δ (= R4-R3) with the direct wave linear distance R3 can be obtained.

  By the way, as described with reference to FIG. 3, the radar apparatus 10 has a reception level of the received reflected wave that is a threshold value for detecting the presence of the target (for example, −50 dB described with reference to FIG. 3). When it is between the large threshold values (for example, −45 dB described with reference to FIG. 3), for example, it is determined that the target 5 is approaching the non-detection region, and the frequency of the transmission wave is changed. Below, the example which changes a frequency based on the noise power value of received power is demonstrated.

  FIG. 10 is a diagram illustrating another timing example of variable frequency. In the reception power measurement unit 12 of the millimeter wave radar device 100, when the target is not captured, a noise power value appears as reception power. Here, the average value of the noise power values is referred to as a noise reception level.

  The millimeter wave radar device 100 changes the frequency of the transmission wave when the reception level of the received reflected wave exists between the threshold value 202 greater than the noise reception level 201 and the threshold value 203 greater than the threshold value 202. In other words, for example, when the reception level of the reflected wave that has exceeded the threshold value 203 gradually decreases and the millimeter wave radar device 100 enters between the threshold value 202 and the threshold value 203, the target 5 approaches the non-detection region. And the frequency of the transmission wave is changed. The millimeter wave radar device 100 determines that the target 5 does not exist when the reception level is smaller than the threshold value 202. In this case, the millimeter wave radar device 100 does not change the frequency of the transmission wave.

  The noise reception level 201 may change depending on the surrounding environment or the like. Therefore, the threshold 202 is a value obtained by adding a predetermined level to the noise reception level 201, and the threshold 203 is a value obtained by adding a predetermined level to the threshold 202. For example, the threshold value 202 is set to be the noise reception level 201 + 5 dB. The threshold 203 is set to be, for example, the threshold 202 + 5 dB. Thereby, the millimeter wave radar device 100 can change the frequency appropriately according to the surrounding environment and the like. Note that the difference between the threshold values is not limited to the above example, and the difference between the threshold value 201 and the threshold value 202 and the difference between the threshold value 202 and the threshold value 203 may be different values. Further, for example, when higher accuracy is required as target detection accuracy, it is conceivable to set the difference between the threshold values to a value larger than the above example. Further, for example, when the reflection / scattering cross-sectional area (RCS) of the target is small, it is conceivable to make the difference between the threshold values smaller than in the case of the target having a large reflection / scattering cross-sectional area.

FIG. 11 is a flowchart showing an operation procedure when the frequency of the radar apparatus is switched.
In step S11, the CPU 14 sets a threshold value for performing frequency switching. For example, −50 dB to −45 dB explained in FIG. 3 or the threshold values 202 and 203 explained in FIG. 10 are set.

In step S <b> 12, the radar transmission / reception unit 11 transmits a millimeter wave set to a predetermined frequency from the radar antenna 19.
In step S13, the scanner 18 is activated by the scanner control unit 17 so as to rotate at a predetermined angular velocity.

  In step S14, when the reflected wave returning from the object as the target to the radar antenna 19 is received, steps S15 to S17 are executed next. The reflected wave is received periodically. In step S15, the reception level of the reflected wave is measured by the reception power measuring unit 12. In step S <b> 16, the CPU 14 determines the direction in which the object exists based on the rotation angle data from the scanner control unit 17. Further, in step S17, the frequency of the received reflected wave is measured by the reception frequency measuring unit 13, and the process proceeds to step S18.

In step S18, the separation distance measuring unit 141 measures the separation distance from the radar apparatus to the object.
In step S19, the reception level measured in step S15 is compared with the threshold set in step S11. At this time, if the reception level is outside the threshold range, the process proceeds to step S20, and the millimeter-wave transmission frequency is not switched. For example, when the reception level is greater than the upper limit threshold, the CPU 14 can sufficiently detect the target at the current frequency and does not switch the frequency. Further, when the reception level is smaller than the lower limit threshold, the CPU 14 determines that the target 5 does not exist and does not perform frequency switching.

On the other hand, when the reception level is within the threshold range, the CPU 14 proceeds to step S21 and executes transmission frequency switching.
In step S22, the multipath path length is calculated based on the separation distance to the object measured in step S18 and the rotation angle data measured in step S16.

In step S23, based on the separation distance to the object measured in step S18, a path difference δ between the direct wave and the indirect wave due to the multipath generated between the object and the object is calculated.
In step S24, a ratio value (2δ / λ) between the received wavelengths λ and 2δ is calculated based on the path difference δ calculated in step S23 and the frequency of the reflected wave measured in step S17.

In step S25, the integer value n is obtained by rounding up or down the fractional part from the ratio value (2δ / λ) calculated in step S24.
In step S26, the millimeter wave transmission frequency f in the signal generator 16 is calculated based on the integer value n obtained in step S25.

In step S27, the signal generator 16 is instructed to transmit frequency f calculated by the CPU 14, and the frequency of the transmitted wave is changed.
According to the above procedure, when the received power reflected from the target due to the multipath becomes low when the radar is used, the frequency in the radar apparatus can be switched to correctly detect the target. Note that various modulation schemes such as FM-CW, two-frequency CW, pulse, and spread spectrum (SS) scheme can be employed as a scheme for transmitting a millimeter wave from a radar device to supplement a target.

  Also, the millimeter wave radar device 100 changes the frequency of the transmission wave when the reception level of the reflected wave is within a predetermined range. Thereby, the millimeter wave radar apparatus 100 can suppress power consumption.

The above-described millimeter wave radar device 100 can be used as a radar system that detects vehicles such as automobiles and trains traveling from a distance and notifies them of approach.
FIG. 12 is a diagram illustrating an example in which the radar apparatus is used for vehicle approach detection at an intersection.

  Here, a millimeter wave radar device M is shown which is installed to detect the straight traveling vehicles V1 and V2 approaching the intersection and inform the oncoming vehicle V3 turning right. The millimeter wave radar device M informs the driver of the oncoming vehicle V3 that the straight vehicles V1 and V2 are approaching the intersection by long distance detection.

  This makes it possible not only to be safe when attempting to turn right at an intersection, but also to detect a straight-ahead vehicle because it will not be detected even if the vehicle is within the non-detection range due to multipath effects. It is.

The millimeter wave radar device described above can also be used as a radar system for measuring distance in throwing competitions and the like.
FIG. 13 is a diagram illustrating an example in which the radar apparatus is used for measuring a throwing distance.

  The millimeter wave radar apparatus M detects the thrown shot cannon Ba, and determines the distance to the fall point. Even when the shot cannon Ba is within the non-detection range due to the effect of multipath, it is possible to detect the distance reliably and measure the distance.

  The above processing functions can be realized by a computer. In that case, a program describing the processing contents of the functions that the radar apparatus 10 should have is provided. By executing the program on a computer, the above processing functions are realized on the computer. The program describing the processing contents can be recorded on a computer-readable recording medium. Examples of the computer-readable recording medium include a magnetic storage device, an optical disk, a magneto-optical recording medium, and a semiconductor memory. Examples of the magnetic storage device include a hard disk device (HDD), a flexible disk (FD), and a magnetic tape. Optical discs include DVD, DVD-RAM, CD-ROM / RW, and the like. Magneto-optical recording media include MO (Magneto-Optical disk).

  When distributing the program, for example, a portable recording medium such as a DVD or a CD-ROM in which the program is recorded is sold. It is also possible to store the program in a storage device of a server computer and transfer the program from the server computer to another computer via a network.

  The computer that executes the program stores, for example, the program recorded on the portable recording medium or the program transferred from the server computer in its own storage device. Then, the computer reads the program from its own storage device and executes processing according to the program. The computer can also read the program directly from the portable recording medium and execute processing according to the program. In addition, each time a program is transferred from a server computer connected via a network, the computer can sequentially execute processing according to the received program.

  In addition, at least a part of the above processing functions can be realized by an electronic circuit such as a DSP (Digital Signal Processor), an ASIC (Application Specific Integrated Circuit), or a PLD (Programmable Logic Device).

DESCRIPTION OF SYMBOLS 1 Transmission part 2 Reception part 3 Control part 4 Antenna 5 Target 10 Radar apparatus

Claims (5)

A transmission unit for outputting a transmission wave;
A receiving unit that receives the reflected wave reflected by the target, and
A control unit that changes the frequency of the transmission wave output by the transmission unit when it is detected that the target having a reception level within a predetermined range exists based on the reflected wave received by the reception unit;
I have a,
The radar apparatus according to claim 1, wherein the control unit changes the frequency of the transmission wave based on a difference between a radio path directly reaching the target from the transmission unit and a multipath radio path . Wherein the control unit calculates a difference δ between the radio path of the radio wave path multipath directly reaching the target from the transmitting unit, the set frequency in the transmission section,
2δ / λ = n (n is an integer, λ is the wavelength of the transmission wave)
The radar apparatus according to claim 1, wherein the radar apparatus is changed to be Wherein, the reception level of the reflected wave received by the reception unit, a first threshold value for determining the presence or absence of the target, with the first threshold value larger than the second threshold value The radar apparatus according to claim 1, wherein the frequency of the transmission wave output from the transmission unit is changed when the transmission unit is in between. Wherein, the reception level of the reflected wave received by the reception unit, and a noise reception level larger than the first threshold value of the reflected wave, between the first threshold larger than the second threshold value The radar apparatus according to claim 1, wherein the frequency of the transmission wave output from the transmission unit is changed in some cases. In a frequency control program for a radar apparatus including a transmission unit that outputs a transmission wave and a reception unit that receives a reflected wave reflected by the target of the transmission wave,
Computer
On the basis of the reflected wave received by the receiving unit, when the target reception level of the predetermined range is detected that the present, and a control means to change the frequency of the transmission wave in which the transmitting unit outputs Frequency control program to function
The said control means changes the frequency of the said transmission wave based on the difference of the radio wave path | route which reaches | attains the said target directly from the said transmission part, and a multipath radio wave path | route .

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